PHARM - Oral Medications and the Eye - Week 6 Flashcards
What route of drug administration is more likely to cause adverse effects?
Oral and injectables
How do topical eye drugs enter the blood stream (3)? Give percentages.
Direct absorption across the conjunctival blood vessels (30%)
Draining via naso-lacrimal duct, into nasal cavity, and eventually the gut (70%)
What absorption mode can give direct access to the CNS? Is it fast or slow?
Cross membranes of the olfactory nerve, is fast
True or false
All topical eye drops/ointments will be absorbed into the bloodstream.
True
Describe the double D method for minimising systemic eye drug absorption. Explain why it works briefly.
By how much does this reduce systemic absorption?
Dont open eyes for 1-2 mins (minimises conjunctival flow)
Digital puncta occlusion (reduces punctal access)
Reduces [drug] in blood by 65-70%
Is it easy for drugs to absorb into the cornea?
No, its a challenge
What is the best formulary for corneal absorption? What is a problem with it?
Acetate formulary
While it has rapid absorption, it borders on toxicity
What is the rule of thumb for eye drop formularies in order of use (3)?
Describe the general effect and duration for each formulary (if applicable).
Acetate > alcohol»_space; phosphate
Acetates are more toxic but can be at a lower dose that avoids it, the effect is short lived and may require multiple drops.
Phosphates have a slower absorption with longer duration of non-toxic therapeusis.
What are 6 classes of drugs that optometrists can prescribe?
Allergy
Anti-inflammatory
Analgaesics
Antibiotics
Antivirals
Anti-glaucoma
How can ocular lubricants be useful as an anti-allergy agent?
They can wash/remove/dilute an antigen
Can vasoconstrictors be used for mild non-specific hyperaemia?
Yes
What is a good agent to use for mild allergic conjunctivitis?
Vasoconstrictors like alpha-adrenergic agents
Give an example of an alpha-adrenergic vasoconstrictor.
Phenylephrine
What action do astringents have and what are they useful for?
They reduce mucoid discharge in allergic surface disease and is a useful anti-allergy agent
What is the hallmark of allergic eye disease?
Itch
Mast cell stabilisers are useful as what?
Anti-allergy agents
What histamine receptors are anti-histamine eye drops selective for?
H1 selective
What histamine receptors are mast cell stabiliser eye drops selective for?
H1 selective
What does pre-treatment with mast cell stabiliser eye drops result in?
Minimises expression of allergic eye disease
Are anti-inflammatory agents also anti-allergy?
Generally yes
How do NSAIDs work in the eye (3)? What agent do they act as?
Inhibit COX enzymes, decreasing prostaglandin synthesis, and reducing prostaglandin mediated inflammation.
They are anti-inflammatory agents.
Corticosteroids inhibit what pathway?
Intracellular receptor mediated inhibition of inflammatory cascade
Corticosteroids inhibit the activity of what two cells in the eye?
Fibroblast and keratocyte activity
List two examples of antimetabolites and what agents they act as.
Calcineurin and T-cell inhibitors
As anti-inflammatory agents
What is a good rule of thumb on treating eye inflammation?
If it is no deeper than the iris, topical therapy should suffice.
What should be considered if inflammation is deeper than the iris (4)?
Oral, intraocular/sub-conj./sub-Tenon’s injection
The use of what drug class will control post-op cystoid macular oedema? Describe why.
Topical use of NSAIDs
It inhibits PG production in the anterior eye, rather than the retina, and will reduce overall ocular PG load at the posterior pole
Are steroid complications more or less likely with long duration of use?
More likely
Does topical steroid use promote or inhibit microbial activity? How does it affect would healing?
Promotes microbial activity
Delays would healing
List 5 ocular related adverse effects that occurs with long-term topical steroid use.
Increased IOP - glaucoma
Cystoid macular oedema
Rebound inflammation
Aggravated dry eye
Cataract
How should steroids generally be used?
Use them hard to suppress inflammation but only for short terms <4 weeks
List 3 ocular related adverse effects that occurs with long-term periocular steroid use.
-as for topical use
Ptosis
Scleral melt and perforation
List 6 adverse effects that occurs with long-term oral/systemic steroid use.
Weight gain
Peptic ulcer
Opsteoporosis
Diabetes
Hypertension
Cushing syndrome
Describe a possible dietary link to inflammation. Comment on essential fatty acids 3 and 6, as well as the Western diet in this context.
Cell membranes produce free fatty acids in the presence of PLA2, which is produced in large amounts during inflammation.
n-6 pathway favours pro-inflammatory cytokine production.
n-3 pathway favours anti-inflammatory cytokine production.
The western diet has a high intake of n-6.
What can be used for pain in the case of iritis or uveitis?
Cycloplegic agent
Is penicillin commonly used in eye care?
Rarely